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/*
 * Gray8Threshold.java
 *
 * Created on September 9, 2006, 10:25 AM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 *
 * Copyright 2007 by Jon A. Webb
 *     This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Lesser General Public License as published by
 *    the Free Software Foundation, either version 3 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Lesser General Public License for more details.
 *
 *    You should have received a copy of the Lesser GNU General Public License
 *    along with this program.  If not, see .
 *
 */

package com.github.ojil.algorithm;

import com.github.ojil.core.Gray8Image;
import com.github.ojil.core.Image;
import com.github.ojil.core.ImageError;
import com.github.ojil.core.PipelineStage;

/**
 * Threshold. Output is a Gray8Image with values less than threshold set to
 * Byte.MAX_VALUE, below threshold set to Byte.MIN_VALUE if bWithin is true,
 * opposite if bWithin is false.
 * 
 * @author webb
 */
public class Gray8Threshold extends PipelineStage {
    boolean bWithin;
    int nThreshold;
    
    /**
     * Creates a new instance of Gray8Threshold
     * 
     * @param nThreshold
     *            threshold value.
     * @param bWithin
     *            direction of threshold. If true then output is true
     *            (Byte.MAX_VALUE) iff < threshold.
     */
    public Gray8Threshold(final int nThreshold, final boolean bWithin) {
        this.nThreshold = nThreshold;
        this.bWithin = bWithin;
    }
    
    /**
     * Threshold gray image. Output is Byte.MAX_VALUE over threshold,
     * Byte.MIN_VALUE under.
     *
     * @param image
     *            the input image (and output)
     * @throws ImageError
     *             if the image is not a gray 8-bit image.
     */
    @Override
    public void push(final Image image) throws ImageError {
        if (!(image instanceof Gray8Image)) {
            throw new ImageError(ImageError.PACKAGE.ALGORITHM, AlgorithmErrorCodes.IMAGE_NOT_GRAY8IMAGE, image.toString(), null, null);
        }
        final Gray8Image gray = (Gray8Image) image;
        final Byte[] data = gray.getData();
        for (int i = 0; i < data.length; i++) {
            data[i] = (((data[i]) < nThreshold) == bWithin) ? Byte.MAX_VALUE : Byte.MIN_VALUE;
        }
        super.setOutput(image);
    }
    
    /**
     * 
     * @return String describing class instance.
     */
    @Override
    public String toString() {
        return super.toString() + "(" + nThreshold + ")"; //$NON-NLS-1$ //$NON-NLS-2$
    }
    
}